I lived on Cheerios for both rounds of firstline chemo (4/5 years apart) & then someone who'd done chemo suggested chips & sure enough I could eat that. I think it mostly depends what you can tolerate food-wise. Not the healthiest of foods, but my oncs thought it preferable to not eating at all.
I would also just force myself to eat neutral things that the whole family was eating, despite the fact that I in no way wanted to eat them. Potatoes, rice, pork chops, whatever veg was offered --